diff --git a/ChangeLog b/ChangeLog
index f98eadf461..957af639d0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Tue Jun  3 12:59:32 2014  Koichi Sasada  <ko1@atdot.net>
+
+	* gc.c (check_gen_consistency): fix error message.
+
 Tue Jun  3 12:40:23 2014  Koichi Sasada  <ko1@atdot.net>
 
 	* gc.c: count old/young objects more correctly.
diff --git a/gc.c b/gc.c
index 2cf1dae9cf..dd1599ab5e 100644
--- a/gc.c
+++ b/gc.c
@@ -749,7 +749,7 @@ check_gen_consistency(VALUE obj)
 
 #if !RGENGC_AGE2_PROMOTION
 	    if (!old_flag) {
-		rb_bug("check_gen_consistency: %p (%s) is not infant, but is not old (on 2gen).", (void *)obj, obj_type_name(obj));
+		rb_bug("check_gen_consistency: %p (%s) is promoted, but is not old.", (void *)obj, obj_type_name(obj));
 	    }
 #endif
 
@@ -759,7 +759,7 @@ check_gen_consistency(VALUE obj)
 	}
 	else {
 	    if (old_flag) {
-		rb_bug("check_gen_consistency: %p (%s) is not infant, but is old.", (void *)obj, obj_type_name(obj));
+		rb_bug("check_gen_consistency: %p (%s) is not promoted, but is old by bitmap.", (void *)obj, obj_type_name(obj));
 	    }
 	}
     }